Firearm



Feb. 14, 1939. M. M. JOHNSON, JR

FIREARM Fi1edJan. 5, 1931s NNO.

UNITED STATES PATENT OFFICE FIREARM Melvin M. Johnson, Jr., Brookline,Mass., assignor to Melvin M, Johnson, Brookline, Mass., Ed-

ward E. Rice, Boston, Mass., and himself, as

trustees of Johnson Patent Trust Application January 5,

Claims.

In automatic firearms where the breech opens shortly after detonationmuch difficulty is encountered in extracting shells owing to theexpansion of the shells in the firing chamber by in the initial stage ofbolt recoil, serves to kickthe plunger to the rear as aforesaid,therebyto facilitate extraction. Thus the cam lug on the boltconstitutes an actuator which has a transverse (rotary) component ofmovement at the 1938, Serial No. 183,469

forward end of its reciprocation, and the plunger constitutes a kickerwhich recoils relatively to the bolt in response to said transversecomponent of movement.

position until the bolt returns to forward position, the barrel thenbeing pushed to its forward position by the bolt after the lugs I5 onthe bolt have passed through the spaces between the lugs 5 gas pressure.The object of the present inven- For the purpose of illustration atypical em- 6 tion is to overcome this dimculty. bodiment of theinvention is shown in the accom- My invention is based on the principlethat panying drawing in which, friction between sliding surfaces canbest be over- Fig. 1 is a top plan view with parts broken come by animpact in contradistinction to a away and parts in section, showing thebreech Steady force. For example if a shell sticks in a mechanism inclosed position; l0 ring chamber it can be removed with a ramrod Fig. 2is a similar view showing the parts in more easily by lightlytapping onthe ramrod the positions which they occupy at the moment than by'steadily pushing with a heavier force. extraction begins; Accordingto-the present invention AI provide Fig. 3 is a similar view showing theparts in Al5 means for applying to the bolt, at the beginning' thepositions which they occupy at the moment l5 of each extraction, a sharpblow to the rear, of ejection; and thereby to start the sliding movementof the Figs. 4 and 5 are sections on lines 4 4 and shell in the chamber.This is accomplished by 5-5 of Fig. 2. including, in fthe breechmechanism, a kicker 'I'he particular embodiment of the invention whichrecoils relatively to the bolt diuing the chosen for the purpose ofillustration comprises 20 initial stage of recoil and which has a reara`receiver I, a barrel comprising two parts 2 and wardly-facing abutmentfor impact against a IlA threaded together at 4, a bolt 5, an extractor6l forwardly-facing abutment on the bolt, the abutmounted on the bolt,an ejector 'i mounted in an A ments being spaced apart when the bolt isin opening 8 in the-side of the receiver, a handle 9 closed position andthe spacing being correlated for manually retracting the bolt, theaforesaid 9 5 with the relative movement of said part and bolt plungeror kicker I0, a strut II pivotally conto cause the first abutment toimpinge against nected to the rearward end of the plunger I0 byv thesecond abutment when extraction is to be pin I2, the strut Il extendingback to the recoil initiated. The aforesaid part preferably comspringnot shown, and a firing pin I3. The rear- Y prises a plunger interposedbetween the nolt and ward end o1' the barrel sleeve 3 has an annular 30recoil spring which is kicked back in the initial row of inwardlyprojecting locking lugs I4 and recoil movement of the breech mechanism,prefthe forward end of the bolt has an annular row erably by a rotarycomponent of the initial4 moveof outwardly projecting locking lugs I5.In the ment of the bolt. closing movement of the bolt the lugs I5 passThe invention is particularly applicable to flrebetween the lugs I4,after which the boli; is ro- 35 arms of tlie reciprocating barrel typein which tated in a counter-'clockwise direction (Figs. 4 the bolt haslocking lugs seating against locking and 5) to bring the bolt lugs I5 infront of the abutments on` the barrel, a part of the bolt barrel lugsI4, thereby interlocking the bolt to (either the whole bolt or merelythe bolt head) the barrel. When the gun is fired the bolt and. 40 havingrotary or other transverse movement to barrel recoil together from theposition shown in 40 bring the locking lugs into locking engagement Fig.1 to the position shown in Fig. 2, and during with said abutments at theend of the closing this recoil the bolt is rotated, by mechanismmovement of the bolt and out of locking engagehereinafter described, tobring the lugs I5 on the ment in the initial stage of the recoilmovement bolt into alignment with the spaces between the of the bolt. Inthe preferred embodiment of the lugs I4 on the barrel, whereupon thebolt is free 45 invention the aforesaid plunger has a forwardlytorecoil. After the bolt is disengaged from the facing cam surfaceengaging arearwardly-facing barrel the latter may be returned to forwardcam surface on a lug on the bolt which rotates position by a spring (notshown) as described the bolt into locked position at the forward end inmy Patent No. 2,094,156, granted September o of the closing movement ofthe bolt and which, 28, 1937, or the barrel may remain in retracted I4on the barrel, while the bolt is "rotating to f locked position duringthe final stage of its forward motion.

The rotary movement of the bolt to locked position is controlled by lugsI and I1 on the bolt 5 and plunger I0, respectively, the lug I1 having aforwardly-facing cam surface I8 engaging a rearwardly-facing cam surfaceI9 on the bolt lug I6 tending to rotate the bolt into locked position.Mounted on the lugs I6 and I'l are rollers 20 and 2l which fit into agroove in the top of the receiver (Figs. 4 and 5) to prevent rotation ofthe bolt and plunger during recoil. However, as shown in Fig. V5, theforward end of this groove has a lateral offset to permit rotation ofthe bolt to locked position at the forward end of its closing movement.To rotate the bolt out of locked position while the bolt and barrelrecoil together, the lug I6 is provided with another cam surface 22engaging a cam surface 23 which is fixed to the receiver. Thus, as thebolt recoils from .the position shown in Fig. 1 to the position shown inFig. 2, the cam surfaces 22 and 2t rotate the bolt suiciently to bringthe lugs I5 on the bolt into alignment with the spaces between the lugson the receiver. Engagement of the roller 2B with the side of theaforesaid groove of the receiver stops the rotary movement and the boltcontinues to the rear by straight-lined movement alone. In theparticular embodiment of the invention shown in the drawingjthe camsurface 23 is formed on a lug 24 depending from a cover plate 25 whichis mounted on the receiver by a dovetailed connection 26 (Fig. 5), thecover sliding into the receiver from front to rear and being held inposition by a screw 21. The lug 24 seats to the rear against a shoulder28 in the receiver so that the rearward thrust on the lug by the boltlug I6 is transmitted directly to the receiver.

According to this invention, the bolt is provided with aforwardly-'facing shoulder 29 engageable by the rear end of the lug I'Ito facilitate extraction. 'Ihis shoulder is spaced from the lug I6 onthe bolt a distance slightly greater than the length of the lug I1 onthe plunger so that at the moment the bolt is unlocked from the barrel(as illustrated in Fig. 2) there is sufficient space for back and forthmovement of the lug I1 between the lug I6.and the shoulder 29. 'Ihisfreedom of movement is utilized to facilitate extraction in thefollowing manner: During the initial stage of recoil movement, while thebolt barrel and plunger are recoiling together and the bolt is rotatingfrom locked to unlocked position, the plunger lug I'I is moving to therear somewhat faster than the bolt because of the camming action betweenthe surfaces I8 and IS on the lugs I6 and I1 respectively. Furthermore,at the moment the bolt is unlocked from the barrel its rearwardcomponent of movement is checked, through the medium of the extractor,by the tendency of the cartridge shell to stick in the firing chamber.Inasmuch as the plunger lug I1 is traveling faster than the bolt and isnot checked by the cartridge, it continues to the rear,'impinging onAthe shoulder 29. By virtue of this rearward impact on the bolt at themoment extraction begins the shell is loosened in the firing chamber andthe extraction is thereby facilitated. Y Immediately following thisimpact the bolt catches up with the plunger because of the resistance ofthe recoil spring acting on the plunger through the strut II and thebolt and plunger then continue to the rear to the position shown in Fig.3 where the shell is ejected.

The body of the ejector 'I substantially fills the recess 8 in the sideof the receiver and the forward end of the projector is provided with anarrow nn 30 on its inner face which engages the shell. The rear end ofthe ejector lies in a longitudinal groove 3l in the bolt, the forwardend of the groove being gradually reduced in depth to'cam the ejectorinto the ejecting position shown in Fig. 3 as the bolt nears the end ofits recoil movement.

It should be understood that the present disclosure is for the purposeof illustration only and that this invention includes all modincationsand equivalents which fall within the scope of the appendedy claims.

I claim:

1. A firearm comprising a bolt, an extractor on the bolt, and breechmechanism permitting automatic recoil of the bolt when the rearm isdischarged, said mechanism including akicker which recoils relatively tothe bolt before the bolt leaves the firing chamber and which has arearwardly-facing abutment for engagement with a forwardly-facingabutment on the bolt, said abutments being spaced apart when the bolt isin closed position and the spacing being correlated with the relativemovement of said part and bolt to cause the first abutment to impingeagainst the second abutment substantially when the bolt leaves thefiring chamber thereby to facilitate extraction.

2. A iirearm comprising a bolt, an extractor on the bolt, a recoilspring, and breech mechanism normally locking the bolt in firingposition and automatically unlocking the bolt when the vfirearm isdischarged, said mechanism including a plunger interposed between thebolt and recoil spring which recoils relatively to the bolt during theinitial stage of recoil and which has a rearwardly-facing abutment forengagement with a forwardly-facing abutment on the bolt, said abutmentsbeing spaced apart when the bolt is in closed position and the spacingbeing correlated with the relative movement of said plunger and bolt tocause the first abutment to impinge against the second abutment duringsaid initial stage of recoil thereby to facilitate extraction.

3. A firearm comprising a reciprocating bolt having a rotary componentof movement at the f forward end of its reciprocation, an extractor onthe bolt, and automatic breech mechanism controlling the movement of theboltl said mechanism including a non-rotary kicker which recoilsrelatively to the bolt during the initial stage of recoil and which hasa rearwardly-facing abutment" for engagement with a forwardly-facingabutment on the bolt, said abutments being vspaced apart when the boltis in closed position and the spacing being correlated with the relativemovement of said part and bolt to cause the rst abutment to impingeagainst the second abutment during said initial stage of recoil therebyto facilitate extraction.

4. A firearm comprising a reciprocating bolt, an extractor on the bolt,and breech mechanism permitting automatic recoil of the bolt when therearm is discharged, said mechanism including an actuator reciprocatingwith the bolt and also having a transverse component of movement at theforward end of its reciprocation and said mechanism also including akicker which recoils relatively to the bolt in response to saidtransverse component of movement and which has a rearwardly-facingabutment for engagement with a forwardly-facing abutment on the bolt,said abutments being spaced apart when the bolt is in closed positionand the spacing being correlated with the relative movement of said boltand kicker to cause the rst abutment to impinge against the secondabutment during said initial stage of recoil thereby to facilitateextraction.

5. A firearm comprising a receiver, a recoiling barrel, lockingabutments on the barrel, a reciprocating bolt having rotary movement atthe forward end of its reciprocation, an extractor, locking lugs on thebolt for engagement with said abutments, a recoil spring, and a plungerbetween the bolt and spring, the bolt and plunger having cooperating camsurfaces for moving said lugs into locking engagement with saidabutments by rotating the bolt at the forward end of its reciprocation,said receiver and bolt having cooperating cam surfaces for rotating thebolt while the bolt and barrel recoil together, thereby disengaging saidlugs from said abutments and, through the medium of said first camsurfaces, kicking said plunger to the rear relatively to the bolt, theplunger having a rearwardly1facing surface impinging on aforwardly-facing surface of the bolt for facilitating extraction.

MELVIN M. JOHNSON, JR.

